POWER LOSS (W) LTC3823 TM Fast No R Step-Down SENSE Synchronous DC/DC Controller with Differential Output Sensing, Tracking and PLL FEATURES DESCRIPTION n Wide V Range: 4.5V to 36V The LTC 3823 is a synchronous step-down switching regu- IN n 0.67%, 0.6V Reference Voltage lator controller with true remote differential output sensing n Output Voltage Tracking Capability and output voltage up/down tracking capability. Its advanced n True Remote Sensing Differential Ampli er functions and high accuracy reference are ideal for powering n Sense Resistor Optional high performance server, ASIC and computer memory n True Current Mode Control systems. n 2% to 90% Duty Cycle at 200kHz The LTC3823 uses a constant on-time, valley current n t < 100ns ON(MIN) mode control architecture to deliver very low duty fac- n Phase-Locked Loop Frequency Synchronization tors without requiring a sense resistor. The operating n Powerful Dual N-Channel MOSFET Driver frequency is selected by an external resistor and is com- n Adjustable Cycle-by-Cycle Current Limit pensated for variations in input supply voltage. An internal n Adjustable Switching Frequency phase-locked loop allows the IC to be synchronized to an n Programmable Soft-Start external clock. n Current Foldback Protection (Disabled at Start-Up) n Fault protection is provided by an overvoltage compara- Output Overvoltage Protection n tor and input undervoltage lockout. The regulator current Micropower Shutdown: 30A n limit is user programmable. A wide supply range allows Power Good Output Voltage Monitor Tracks the voltages as high as 36V to be stepped down to as low as Reference Input Pin n a 0.6V output. When using remote sense, output voltages Available in (5mm 5mm) 32-Lead QFN and up to 3.3V can be developed, and up to 90% of V without 28-Lead SSOP Narrow Packages IN remote sense. Power supply sequencing is accomplished APPLICATIONS using an external soft-start timing capacitor. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and n Distributed Power Systems No R is a trademark of Linear Technology Corporation. All other trademarks are the SENSE property of their respective owners. Protected by U.S. Patents including 5481178, 5847554, n Server Power Supplies 6580258, 6304066, 6476589, 6774611. TYPICAL APPLICATION Ef ciency and Power Loss High Ef ciency Step-Down Converter vs Load Current 97 10 PGOOD I ON V = 5V IN 68k V 96 V = 2.5V IN OUT V 0.01F IN 5V TO 28V FIGURE 12 CIRCUIT 10k 10F 95 TG Si4884 PLLFLTR 35V 1.8H s 3 94 PLLIN V OUT 1 EFFICIENCY 0.1F SW 2.5V 93 TRACK/SS 0.22F 10A BOOST + 92 180F I TH POWER LOSS 4V 10k LTC3823 CMDSH-3 91 1000pF s 2 SGND INTV 0.1 CC 90 DRV RUN CC V Si4874 89 OUT V BG ON + SENSE V 88 RNG B340A 10F V DIFFOUT SENSE 87 0.01 9.5k 0.1 1 10 PGND LOAD CURRENT (A) 3823 TA01b V FB + V OUTSENSE 3k V OUTSENSE 3823 TA01a 3823fd 1 EFFICIENCY (%)LTC3823 ABSOLUTE MAXIMUM RATINGS (Note 1) RUN, I .................................................... 0.3V to 12V Supply Voltages ON PLLFLTR, I , V Voltages ...................... 0.3V to 2.7V Input Supply Voltage V , IN TH FB INTV , ZV Voltages ................................0.3V to 7V V ....................................................0.3V to 36V INSNS CC CC TG, BG, INTV Peak Currents ....................................4A DRV , (BOOST SW) ............................0.3V to 7V CC CC TG, BG, INTV RMS Currents ...............................50mA BOOST ................................................... 0.3V to 42V CC + Operating Temperature Range .................40C to 85C SENSE , SW Voltage .................................5V to 36V Junction Temperature (Note 2) ............................. 125C TRACK/SS, FCB, Z0, Z1/SS , Z2, ENABLE + Storage Temperature Range ..................65C to 125C PLLIN, V , V OUTSENSE OUTSENSE Lead Temperature (Soldering, 10 sec) Voltages .................................. 0.3V to (INTV + 0.3)V CC SSOP ................................................................300C V , V , PGOOD Voltages .. 0.3V to (INTV + 0.3)V ON RNG CC V ................................................0.3V to INTV DIFFOUT CC PIN CONFIGURATION TOP VIEW TOP VIEW 1 28 Z0 FCB 2 27 BOOST RUN 32 31 30 29 28 27 26 25 3 26 TG + V ON V 1 24 SENSE RNG 4 25 SW PGOOD V 2 23 SENSE FB + 5 24 SENSE V I PGND RNG 3 22 TH 6 23 SENSE V SGND 4 21 BG FB 33 7 22 PGND I 5 20 DRV I ON SGND CC TH V 6 19 INTV 8 21 BG SGND DIFFOUT CC NC 7 18 Z2 9 20 INTV I ON CC + V 8 17 Z1/SS OUTSENSE 10 19 Z2 ENABLE V DIFFOUT 9 10 11 12 13 14 15 16 + 11 18 Z1/SS V OUTSENSE ENABLE 12 17 ZV V OUTSENSE CC 13 16 V TRACK/SS IN 14 15 PLLIN PLLFLTR UH PACKAGE 32-LEAD (5mm s 5mm) PLASTIC QFN GN PACKAGE T = 125C, = 34C/W JMAX JA 28-LEAD PLASTIC SSOP NARROW EXPOSED PAD (PIN 33) IS SGND, MUST BE SOLDERED TO PCB T = 125C, = 80C/W JMAX JA ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LTC3823EGN PBF LTC3823EGN TRPBF LTC3823EGN 28-Lead Plastic SSOP Narrow 40C to 85C LTC3823IGN PBF LTC3823IGN TRPBF LTC3823IGN 28-Lead Plastic SSOP Narrow 40C to 85C LTC3823EUH PBF LTC3823EUH TRPBF 3823 32-Lead (5mm 5mm) Plastic QFN 40C to 85C LTC3823IUH PBF LTC3823IUH TRPBF 3823 32-Lead (5mm 5mm) Plastic QFN 40C to 85C Consult LTC Marketing for parts speci ed with wider operating temperature ranges. *The temperature grade is identi ed by a label on the shipping container. Consult LTC Marketing for information on non-standard lead based nish parts. For more information on lead free part marking, go to: